Evaluation of soil fertility using geostatistical techniques for hazelnut orchard in a waterlogged soil

Assessment of soil fertility status is crucial for sustainable agriculture. geostatistical methods provide a unique opportunity to determine the spatial variability of plant and soil properties and soil fertility. The objective of this study was to determine the spatial variability of soil fertility and plant nutrition status of a hazelnut orchard in a waterlogged soil affected by rainfall during at sometimes of the season. The study area is located in Ordu province, Altınordu district, Cumhuriyet neighbourhood and covers 3.5 ha. Using random sampling technique, surface soil samples (0-20 cm) were collected from 118 sampling points and plant samples from Tombul variety were collected from each tree. Selected properties of soil and plant samples were determined on the basis of laboratory analysis data and some field tests. Soil properties such as soil texture, bulk density, pH, electrical conductivity (EC), organic matter, NH4-N+NO3-N, available P, Ca, Mg, Na, K, Fe, Cu, Zn, Mn, B, Ca:K, Ca:Mg, Mg:K ratio, microbial biomass C, Cmic:Corg; leaf properties such as chlorophyll a, chlorophyll b, total chlorophyll, chlorophyll a:b; N, P, K, Ca, Mg, Na, Fe, Cu, Zn, Mn, B were analysed and spatial variation for each selected parameter was modelled and mapped using geostatistical methods. Semivariograms for soil properties and leaf properties showed spatial dependence with ranges of influence of about 19.8-742.7 m and 17.1-1532.7 m, respectively. The maps showed that soil and plant properties were not similar between waterlogged and non-waterlogged areas. Waterlogged soils had higher EC values. Soil pH ranged from strongly acidic to neutral and the pH value also affected uptake of mineral nutrients. It was determined that hazelnut leaves were generally sufficient in terms of Ca, Mg and micronutrients, but insufficient in terms of N and K in the study area. The results also show that in the study area, it was determined that the prediction maps of plant and soil properties were compatible with each other. In this study, the use of geostatistical maps of soil and plant properties in this and similar hazelnut orchards will be very useful in the context of site-specific management practices for hazelnut cultivation.